1. Field of Invention
The invention relates to a pump and a balancing cover thereof, and in particular, to a pump capable of repeatedly adjusting rotation balanced amount, and a balancing cover thereof.
2. Related Art
A pump, such as a water pump, pumps up water from a low level to a high level. Therefore, the pump is widely used in the daily life to store the water in a water tower and to pump out a pool of water.
The basic requirement of the pump includes the good pumping efficiency. For example, a centrifugal pump has a rotor structure rotating at a proper rotating speed to drive blades to compress the fluid and then draw off the compressed fluid from an outlet so that the predetermined lift (vertical water path) and flow (i.e., the pumping water amount) can be obtained. The rotation balance of the rotor structure itself directly influences the force applied to a shaft of the pump, the vibration and the lifetime. So, the design of the rotor structure is very important.
Referring to FIG. 1A, a conventional centrifugal pump 1 includes a cover 11 and a rotor structure 12. The cover 11 has a plurality of first half blades 111 and an opening 112. The opening 112 is disposed in a central portion of the cover 11. The first half blade 111 is mounted on a circumference of the cover 11 and has at least one slot 1111 (see FIG. 1B). The rotor structure 12 has a plurality of second half blades 121 and a plurality of locking points 122. Each second half blade 121 has a blind hole 1211 and a locking claw 1212, and is mounted on a circumference of the rotor structure 12. The locking point 122 is mounted on the circumference of the rotor structure 12.
During the assembling process, the rotor structure 12 has to be individually balanced. That is, the eccentric mass is detected and calibrated. If the rotor structure 12 has the eccentric mass, a balancing pin 13 is inserted into the blind hole 1211 of the second half blade 121 of the rotor structure 12 at a position opposite to a position lacking the mass. The balancing operation is repeated until the rotor structure 12 satisfies the balanced specification. Next, when the rotor structure 12 and the cover 11 are assembled, the first half blade 111 of the cover 11 and the second half blade 121 of the rotor structure 12 are aligned and closed. Then, the cover 11 is rotated such that the first half blades 111 are respectively engaged with the locking claws 1212 of the second half blades 121. The first half blade 111 and the second half blade 121 form a complete blade, while the slot 1111 of the first half blade 111 engages with the locking point 122 so that the cover 11 is stably mounted on the rotor structure 12.
However, the rotor structure 12 is individually balanced, the cover 11 makes the overall pump 1 have the residual unbalanced amount after it is assembled with the cover 11. If the rotor structure 12 and the cover 11 have to be balanced again, the cover 11 and the rotor structure 12 have to be disassembled from each other so that the balancing pin 13 can be inserted. Typically, the balancing operation of the rotor structure 12 cannot be completed once. In addition, the balancing pin 13 cannot be easily taken out and then balanced again. If the balancing pin 13 has to be taken out, the cover 11 and the rotor structure 12 have to be disassembled and the cover 11 is thus damaged and cannot be used again. Accordingly, the cover 11 has to be replaced with another cover and the manufacturing cost is thus increased. Furthermore, because the complete blade is formed by the first half blade 111 of the cover 11 and the second half blade 121 of the rotor structure 12, an assembled seam is formed on a pressure surface (i.e., a drainage surface) to influence the water flow of pumping and thus to decrease the efficiency of the pump 1.